Mix 2 gallons water with the beef base in a stock pot until dissolved. Add the brisket and simmer over medium heat until tender, 3 to 4 hours.
Remove the brisket from pot, slice against the grain and set aside. Thicken the jus with some roux, adding a little bit at a time, until it reaches gravy consistency. Place some slices of the meat on a slice of bread and pour the gravy over the brisket. Top with another slice of bread and serve.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.